Thread: Is this if/strcmp correct?

Nope. strcmp has three different return values. Read the man page.

Quzah.

By "continue past", you mean not do the code in the scope of the if statement, correct?

If that's the case, then you'd want == because, if there is no match, then that statement would return true and go into the if scope.

...and no, comparing to 1 would be incorrect because strcmp() doesn't return 1 when they don't match it returns the difference of the bytes. In other words, it could be any number that isn't 0.

No it won't. You have to use and. Pass it "surname" and watch it fail on the first check.


Quzah.

...It won't fail because strcmp() won't return 0. And TRUE || FALSE || TRUE returns TRUE and enters the statement.

Yes it will fail. It will fail to do what they said they wanted it to. It will fail on the first test, and enter the if statement if anything other than "firstname" is entered for the first check. They said they want it to "continue past" if blah blah. Well it won't. It will always enter the first loop. Don't believe me?

Code:

#include<stdio.h>
#include<string.h>

int main( void )
{
    char *foo[] = { "firstname", "surname", "middlename" };
    size_t x;

    for( x = 0; x < sizeof( foo ) / sizeof( foo[0] ); x++ )
        if ( (strcmp ( foo[ x ],"firstname")  != 0)
        ||   (strcmp ( foo[ x ],"surname")    != 0)
        ||   (strcmp ( foo[ x ],"middlename") != 0) )
        {
            printf("Failed.\n");
        }
    
    return 0;
}

Read'm and weep.

Like I said, you have to use and. The confusion comes from the OP's wording. The test doesn't "fail" as in evaluate to false always. It fails in the sense that it will never do what they want it to do.


Quzah.

/bonk

You're missing the point entirely. Your check is wrong. Anything you supply as an argument will run the body of the if. There is no way to avoid it. Changing to strstr isn't going to fix the problem. In fact, even though it's not really possible, it'll make it even "more broken".

Why is it no one ever listens to what I say around here? Hell, I didn't even chew anyone out in this thread yet.


Quzah.

Originally Posted by quzah

It will fail on the first test, and enter the if statement if anything other than "firstname" is entered for the first check. They said they want it to "continue past" if blah blah. Well it won't. It will always enter the first loop. Don't believe me?
...
Read'm and weep.

*yawn*

I'm going to cherish the moment.

If you reread the posts, you'll see that I asked what the OP meant by "continue past". He then replied with this:

Code:

if x isn't "x" or "y" or "z" then
....
else
.....

Implying HE WANTS TO ENTER THE STATEMENT if the variable isn't one of the three literals. I also understood "continue past" to skip over the if, then he said he meant to enter into the if. There for, the condition should be correct.